Photography



Patented Nov. 9, 1943 PHOTOGRAPHY John I. Crabtree and Richard W. Henn, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application November 25, 1941,

Serial No. 420,370

6 Claims.

This invention relates to improved photographic compositions, and, in particular, improved photographic developers giving reduced graininess by development.

It is necessary or desirable for many purposes to obtain photographic films, plates, and the like, having an image which has small or fine grain structure; for instance, when films are projected or enlarged low graininess is advantageous. Certain developers are known to give a reduction in graininess but they have one or more disadvantages, such as increasing fog or volatilization of the grain reducing agent during use. Also, many grain reducing agents heretofore used have required high concentrations.

Our invention has for its object to provide improved agents for reducing graininess; another object is to provide a photographic composition and, in particular, a photographic developer whereby the foregoing difliculties can be largely avoided. Another object is to provide an improved fine grain photographic developer. Other objects will become apparent from the following description and claims.

These and other objects are accomplished by our invention which includes a photographic agent for reducing graininess which contains as an essential constituent a member of the family of symmetrical triamino benzenes.

In the following description we have given several of the preferred embodiments of our invention, but it is to be understood that these are set forth for the purpose of illustration and not in limitation thereof.

Examples of suitable substances reducing graininess and being within the scope of our invention are symmetrical triamino benzene, its homologues, derivatives and their salts, including those derivatives which are attached to the nitrogen atoms as well as the benzene ring. These derivatives may contain one or several substituent groupings. Examples of substituents are halides, methyl, ethyl, and carboxylic groups. Specific examples of such substances are 1,3,5-triamino benzene: 2,4,6-triamino toluene; 2,4,6-triamino benzoic acid and 2,4,6-triamino chlcrbenzene and their salts, such as the hydrochloride, sulfate, etc. The first three specific substances are the most active of those mentioned. It is to be understood that the expression a symmetrical triamino benzene as used in the claims shall apply to all such substances.

In utilizing these agents we prefer to add them to the developing substances which are to be used for the development of silver halide emulsions to produce reduced graininess. They may merely be added to the developing solution or they may be incorporated with the developer when it is packaged in concentrated or like form.

These agents are particularly effective with Elon or other developers of low or moderate activity, but they may be used with other developing agents such as paraphenylenediamine or its derivatives to give further reduction in graininess, or with combinations including two or more developing agents. They may also be used in combination with alkali bromides or other graininess-reducing agents. The most useful concentrations range from about 1 to about 10 grams per liter, although greater or lesser Example 1 Mcnomethyl p-aminophenol, sulfate ams" 2.0 Sodium sulfite (anhydrous) do 100.0 Hydroquinone do 5.0 Borax do 2.0 2,4,6-triamino toluene, trihydrochloride....

' o--- 5.0 Water to liter 1.0

Dissolve in order given in water at about 125 F. This solution'requires about 18 minutes developing time at F., and gives low graininess. Increasing the concentration of the triamino toluene to 10 grams per liter effects a further decrease in graininess.

Example 2 Symmetrical triamino benzene trihydrochloride grams 5 Monomethyl p. amlnophenol, su1fate do- 5 Sodium sulfite (anhydrous) do Sodium metaborate do 2 Water t er..- 1.0

This solution was used to develop Super-XX roll film, and was compared with a solution of the same composition in which the triamino benzene was omitted, called hereafter the"basic developer. The developer containing the triamino benzene required about 40 per cent more development time than the basic developer but reduced the graininess very considerably and reduced the fog from 0.06 to 0.02. This decrease in graininess was accompanied by a loss of 50 per cent in emulsion speed.

Example 3 Symmetrical triamino benzene trihydrochloride grams 1.0 N (ethyl, 3-methyl-4-aminophenyl) glycineamide do 5.0 Sodium sulfite do 100.0 Sodium metaborate do 20.0 Water to liter 1.0

This solution, developing Super-XX roll film in about 20 minutes at 68 F. (with high agitation), gave a low degree of graininess and satisfactorily low fog. When the concentration of triamino benzene (trihydrochloride) was increased to 5 grams per liter the graininess was reduced to an extremely low level with only a slight increase in developing time.

The substances described herein have the advantage that they effect a greater reduction in grain size than other agents heretofore used for this purpose; also, they canbe used in smaller amounts than previously known agents; they.

are also non-volatile and can be used both as salts or as the base in' the developer if desired.

A particular advantage is that they have relatively low fogging action.

What we claim is:

1. A photographic developer adapted to reduce graininess containing as an essential constituent a symmetrical triamino benzene in addition to a, developing agent.

2. A photographic developing composition containing a. developing agent of relatively low activity and a symmetrical triamino benzene.

3. A fine-grain photographic developer comprising a developing agent and a member of the group consisting of 2,4,6-triamino benzene; 2,4,6- triamino toluene; 2,4,6-triamino benzoic acid and 2,4,6-triamlno chlorbenzene.

4. A fine-grain photographic developer comprising a developing agent and symmetrical triamino benzene.

5. A fine-grain photographic developer comprising a developing agent and symmetrical triamino toluene.

6. A fine-grain photographic developer com-" prising a developing agent and symmetrical triamino benzoic acid.

JOHN I. CRABTREE. RICHARD W. HENN. 

